How many RAID Groups I can create ? - Storage

This is a discussion on How many RAID Groups I can create ? - Storage ; We just purchase another 5 SCSI HD for an existing SAN. We will configure
those HD to RAID 5.
We would like to know does it mean that we can only create 1 RAID Group (And
of course we can ...

How many RAID Groups I can create ?

We just purchase another 5 SCSI HD for an existing SAN. We will configure
those HD to RAID 5.

We would like to know does it mean that we can only create 1 RAID Group (And
of course we can create a number of LUNs in that Group) ?

Thanks

Re: How many RAID Groups I can create ?

That sounds like a very storage vendor specific question.

"Peter" wrote in message
news:uqlA%23ucyGHA.3568@TK2MSFTNGP03.phx.gbl...
> We just purchase another 5 SCSI HD for an existing SAN. We will configure
> those HD to RAID 5.
>
> We would like to know does it mean that we can only create 1 RAID Group
> (And of course we can create a number of LUNs in that Group) ?
>
> Thanks
>

Re: How many RAID Groups I can create ?

Dear John,

Thank you for your reply.

Initially, I think that a RAID Group is the number of RAID 5 array that can
be created. As far as I know, for RAID 5, at least 3 HD is required for
RAID 5, it is the reason why I believe that we can only create only 1 RAID
Group.

Peter

"John Fullbright [MVP]" wrote in message
news:eN46yDwyGHA.4976@TK2MSFTNGP04.phx.gbl...
> That sounds like a very storage vendor specific question.
>
>
> "Peter" wrote in message
> news:uqlA%23ucyGHA.3568@TK2MSFTNGP03.phx.gbl...
>> We just purchase another 5 SCSI HD for an existing SAN. We will
>> configure those HD to RAID 5.
>>
>> We would like to know does it mean that we can only create 1 RAID Group
>> (And of course we can create a number of LUNs in that Group) ?
>>
>> Thanks
>>
>
>

Re: How many RAID Groups I can create ?

Again, the answer is dependent upon the storage array that you are using.
Different vendors have different solutions. For example, EMC Clariion arrays
create "Raid Groups" which take slices of physical spindles to form a RAID
groups. You could have many different "Raid Groups" on these spindles.

If you're talking about a generic RAID configuration with 5 disks, you could
potentially create one RAID5 group using 3 disks and one RAID1 group using
the other two disks.

Regards,
John

"Peter" wrote in message
news:uszvvQwyGHA.4796@TK2MSFTNGP06.phx.gbl...
> Dear John,
>
> Thank you for your reply.
>
> Initially, I think that a RAID Group is the number of RAID 5 array that
can
> be created. As far as I know, for RAID 5, at least 3 HD is required for
> RAID 5, it is the reason why I believe that we can only create only 1 RAID
> Group.
>
> Peter
>
> "John Fullbright [MVP]" wrote in message
> news:eN46yDwyGHA.4976@TK2MSFTNGP04.phx.gbl...
> > That sounds like a very storage vendor specific question.
> >
> >
> > "Peter" wrote in message
> > news:uqlA%23ucyGHA.3568@TK2MSFTNGP03.phx.gbl...
> >> We just purchase another 5 SCSI HD for an existing SAN. We will
> >> configure those HD to RAID 5.
> >>
> >> We would like to know does it mean that we can only create 1 RAID Group
> >> (And of course we can create a number of LUNs in that Group) ?
> >>
> >> Thanks
> >>
> >
> >
>
>

Re: How many RAID Groups I can create ?

Dear John,

Thank you for your advice.

We are using EMC Clariion and I am not aware that it is different from
vendor to vendor.

Peter

Re: How many RAID Groups I can create ?

Unless things have radically changed with the new CX3 Clariions, whole
spindles are actually dedicated to RAID groups. Clariion RAID groups
are not slices of physical spindles, but that'd be an interesting
feature. You can carve as many LUNs from a RAID group as you want, but
all those LUNs will have the same protection scheme. Other vendors'
midrange arrays allow for LUNs with differing RAID protection on the
same physical spindles, but EMC does not with the Clariion.

John Toner [MVP] wrote:
> Again, the answer is dependent upon the storage array that you are using.
> Different vendors have different solutions. For example, EMC Clariion arrays
> create "Raid Groups" which take slices of physical spindles to form a RAID
> groups. You could have many different "Raid Groups" on these spindles.
>
> If you're talking about a generic RAID configuration with 5 disks, you could
> potentially create one RAID5 group using 3 disks and one RAID1 group using
> the other two disks.
>
> Regards,
> John
>
>
> "Peter" wrote in message
> news:uszvvQwyGHA.4796@TK2MSFTNGP06.phx.gbl...
>> Dear John,
>>
>> Thank you for your reply.
>>
>> Initially, I think that a RAID Group is the number of RAID 5 array that
> can
>> be created. As far as I know, for RAID 5, at least 3 HD is required for
>> RAID 5, it is the reason why I believe that we can only create only 1 RAID
>> Group.
>>
>> Peter
>>
>> "John Fullbright [MVP]" wrote in message
>> news:eN46yDwyGHA.4976@TK2MSFTNGP04.phx.gbl...
>>> That sounds like a very storage vendor specific question.
>>>
>>>
>>> "Peter" wrote in message
>>> news:uqlA%23ucyGHA.3568@TK2MSFTNGP03.phx.gbl...
>>>> We just purchase another 5 SCSI HD for an existing SAN. We will
>>>> configure those HD to RAID 5.
>>>>
>>>> We would like to know does it mean that we can only create 1 RAID Group
>>>> (And of course we can create a number of LUNs in that Group) ?
>>>>
>>>> Thanks
>>>>
>>>
>>
>
>

Re: How many RAID Groups I can create ?

Hi,

Would it be possible to give me some advice on what "Protection Scheme" is ?

Thanks

"JM" wrote in message
news:%23CasGBEzGHA.4576@TK2MSFTNGP06.phx.gbl...
>
> Unless things have radically changed with the new CX3 Clariions, whole
> spindles are actually dedicated to RAID groups. Clariion RAID groups are
> not slices of physical spindles, but that'd be an interesting feature.
> You can carve as many LUNs from a RAID group as you want, but all those
> LUNs will have the same protection scheme. Other vendors' midrange arrays
> allow for LUNs with differing RAID protection on the same physical
> spindles, but EMC does not with the Clariion.
>
> John Toner [MVP] wrote:
>> Again, the answer is dependent upon the storage array that you are using.
>> Different vendors have different solutions. For example, EMC Clariion
>> arrays
>> create "Raid Groups" which take slices of physical spindles to form a
>> RAID
>> groups. You could have many different "Raid Groups" on these spindles.
>>
>> If you're talking about a generic RAID configuration with 5 disks, you
>> could
>> potentially create one RAID5 group using 3 disks and one RAID1 group
>> using
>> the other two disks.
>>
>> Regards,
>> John
>>
>>
>> "Peter" wrote in message
>> news:uszvvQwyGHA.4796@TK2MSFTNGP06.phx.gbl...
>>> Dear John,
>>>
>>> Thank you for your reply.
>>>
>>> Initially, I think that a RAID Group is the number of RAID 5 array that
>> can
>>> be created. As far as I know, for RAID 5, at least 3 HD is required
>>> for
>>> RAID 5, it is the reason why I believe that we can only create only 1
>>> RAID
>>> Group.
>>>
>>> Peter
>>>
>>> "John Fullbright [MVP]" wrote in message
>>> news:eN46yDwyGHA.4976@TK2MSFTNGP04.phx.gbl...
>>>> That sounds like a very storage vendor specific question.
>>>>
>>>>
>>>> "Peter" wrote in message
>>>> news:uqlA%23ucyGHA.3568@TK2MSFTNGP03.phx.gbl...
>>>>> We just purchase another 5 SCSI HD for an existing SAN. We will
>>>>> configure those HD to RAID 5.
>>>>>
>>>>> We would like to know does it mean that we can only create 1 RAID
>>>>> Group
>>>>> (And of course we can create a number of LUNs in that Group) ?
>>>>>
>>>>> Thanks
>>>>>
>>>>
>>>
>>

Re: How many RAID Groups I can create ?

Sorry, I should have said RAID protection scheme. Basically, any LUNs
sharing the same physical spindles are also in the same RAID group.
Since they're in the same RAID group they are all going to be using the
same RAID protection level (Raid 5, 3, whatever).

Peter wrote:
> Hi,
>
> Would it be possible to give me some advice on what "Protection Scheme" is ?
>
> Thanks
>
> "JM" wrote in message
> news:%23CasGBEzGHA.4576@TK2MSFTNGP06.phx.gbl...
>> Unless things have radically changed with the new CX3 Clariions, whole
>> spindles are actually dedicated to RAID groups. Clariion RAID groups are
>> not slices of physical spindles, but that'd be an interesting feature.
>> You can carve as many LUNs from a RAID group as you want, but all those
>> LUNs will have the same protection scheme. Other vendors' midrange arrays
>> allow for LUNs with differing RAID protection on the same physical
>> spindles, but EMC does not with the Clariion.
>>
>> John Toner [MVP] wrote:
>>> Again, the answer is dependent upon the storage array that you are using.
>>> Different vendors have different solutions. For example, EMC Clariion
>>> arrays
>>> create "Raid Groups" which take slices of physical spindles to form a
>>> RAID
>>> groups. You could have many different "Raid Groups" on these spindles.
>>>
>>> If you're talking about a generic RAID configuration with 5 disks, you
>>> could
>>> potentially create one RAID5 group using 3 disks and one RAID1 group
>>> using
>>> the other two disks.
>>>
>>> Regards,
>>> John
>>>
>>>
>>> "Peter" wrote in message
>>> news:uszvvQwyGHA.4796@TK2MSFTNGP06.phx.gbl...
>>>> Dear John,
>>>>
>>>> Thank you for your reply.
>>>>
>>>> Initially, I think that a RAID Group is the number of RAID 5 array that
>>> can
>>>> be created. As far as I know, for RAID 5, at least 3 HD is required
>>>> for
>>>> RAID 5, it is the reason why I believe that we can only create only 1
>>>> RAID
>>>> Group.
>>>>
>>>> Peter
>>>>
>>>> "John Fullbright [MVP]" wrote in message
>>>> news:eN46yDwyGHA.4976@TK2MSFTNGP04.phx.gbl...
>>>>> That sounds like a very storage vendor specific question.
>>>>>
>>>>>
>>>>> "Peter" wrote in message
>>>>> news:uqlA%23ucyGHA.3568@TK2MSFTNGP03.phx.gbl...
>>>>>> We just purchase another 5 SCSI HD for an existing SAN. We will
>>>>>> configure those HD to RAID 5.
>>>>>>
>>>>>> We would like to know does it mean that we can only create 1 RAID
>>>>>> Group
>>>>>> (And of course we can create a number of LUNs in that Group) ?
>>>>>>
>>>>>> Thanks
>>>>>>
>

Re: How many RAID Groups I can create ?

On the clariion, you designate a RAID type for a given RAID group, and all
LUNs carved from the group share the same RAID type. In constrast, an
architecture like that of the HP EVA allows you to put disks into a disk
group (one big RAID 0) and then create virtual disks of any allowable RAID
type from space within that pool.

With Netapp storage, you start with RAID groups of either RAID DP or RAID 4
and combine multipe RAID groups into an Aggregate. An Aggregate is
essentially a big pool of storage. From the Aggregate, you care Flexvols
wich are a stripe across the pool of disk. Within Flexvols, you create
LUNs.

"Peter" wrote in message
news:%23$aik%23BzGHA.3280@TK2MSFTNGP02.phx.gbl...
> Dear John,
>
> Thank you for your advice.
>
> We are using EMC Clariion and I am not aware that it is different from
> vendor to vendor.
>
> Peter
>
>